Fog freeable runway for aircraft and plant associated therewith



March 29, 1949. A. c. HARTLEY ET AL 2,465,587

FOG FREEABLE RUNWAY FOR AIRCRAFT AND PLANTS ASSOCIATED THEREWITH Filed Feb. 8, 1946 8 Sheets-Sheet 1 igcg March 29, 1949. A. c. HARTLEY ET AL 2,465,587

FOG FREEABLE RUNWAY FOR AIRCRAFT AND PLANTS ASSOCIATED THEREWITH Filed Feb. a, 194e s sheets-sheet 2 A. c. HARTLEY ET Al. 2,465,587 FOG FREEABLE RUNWAY FOR AIRCRAFT `AND PLANTS ASSOCIATED THEREWITH March 29, 1949.

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FOG FREEABLE RUNWAY FOR AIRCRAFT V AND PLANTS ASSOCIATED THEREWITH 8 Sheets-Sheet 6 Filed Feb. 8, 1946 omn March 29, 1949- A c. HARTLEY ET Al.

FOG FREEABLE RUNWAY FOR AIRCRAFT V AND PLANTS ASSOCIATED THEREWITH 8 Sheets-Sheet '7 Filed Feb. 8, 1946 IIL IIL

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Filed Feb. 8. 194e Patented Mar. 29, 1949 UNITED PATENT OFFICE FOG FREEABLE RUNWAY FOR ATRURAFT ANDTPLANTTASSOCIATEDTHEREWITH Rassut WilliamThomas. Moore, Billingham, Paul Otto Rosin, London, andGeraldJohnstone Williamson, Billingham, England, assigncrs to the Minister of Supply in His Majestys Government of-*the United- Kingdom of` Great Britain and Northern Ireland Application- Eebruary,8, 1946, Serial No. 646,420

`IUN 6 1950 In Great Britain February 24, 1945 This invention relates to the dispersalof'fogs ofthe type wholly or mainly composed'ofmoisture in the formof Water droplets. It is well recognised that fogs constitute a menace to the landing of aircraft, so much so in-factthat the decision to dispatch aircraft may entirely depend upon the visibility at their# destination orthe visibility conditions likelyV to-l obtain on theirreturn to their'departure station.

The aim of the present invention isqto` provide a fog freeable runaway, or aligliting` lane such that the landing or alighting strip, including the immediate approach, may be clearedof' fog over the whole oran adequate length thereof to an appropriate height for example to afford a ceilingA of =80100 feet, and obtain sufficient visibility for effecting safe landings;

The invention is based upon the vprinciplethat fog isvcapable of dispersal by the generation off sufficient heat units to evaporate the fog-forming y capable of producing afog-free tunnel-or rift over n the landing strip.

The term landing strip is usedtodenote thatv .part of arunway having a prepared"` or defined permanent or temporary alighting surface.

For the major length of a landing-,strip oiga runway single burner lines are adequate but at the approach ends, where a higher ceilinggof dispersal is required, a rectangular burner frame,

each side of whichV comprises doublel lines, is ad'- visable in order to provide additional heat.'`

The whole cr-substantially the whole ofjtheY burners enclosing the landing,V strip may beV re.

quired to be brought into operation in calmI weather conditions, while in certain wind conditions a selected line (or lines) of burners may be effective to disperse the foglby constituting-a heat screen (or screens) upon thewindwardlside only of the landing` strip. For dealing` with fogs in-v strongl-cross winds it may be necessaryvto install an auxiliary line of burners disposed outside the 18Clams.v (01:244-114.)

normal lines parallel with the longitudinal margins of the landing strip in order to ensure that the displacement of the vertical heat effect caused by the wind shall operate over the landing` strip.

The principle underlying the invention applies equally t0 sea fogs and the landing of sea planes asto land fogs and land planes (i.e. aircraft capable of alighting on the ground, landing strips or solid platforms) but physical or mechanical difficulties exist in connection with the installation and maintenance of plant in Water areas, and consequently the application of the inven-y tion will hereinafter be confined with respect to runways for land planes.

`While according to the invention gaseousfuel could effectively be used, particularly where natural gas is available, it is more feasible, for normal installation to employ liquid hydrocarbon, fuel, of whichclass a volatile liquid such as gasolenehas been found to be suitable. AppropriateY fuelsare hereinafter referred to as liquid fuels.

In o rder to disperse fog, it is essential to develop a smokeless flame, and where a large installation-consuming vast quantities of liquid fuel 'for the required heat-is concerned, the suc-L cessful vaporisation and combustion of liquid fuel;v

presents difficulties. It was at first thought that;

the adoption of the vaporiser blowlamp principlen wasv not practicable. However, after extensive .ex-

periment it was found that by the adoption of` certain jet sizes and relative dimensions and disposition of the burner jet and vaporiser elements.l

smokeless, highly or partially, luminous flames could be promoted, while by the introduction, o rY induction of auxiliaryv air, stable practically colourless, or colourless or Bunsen flames couldbe ensured.

Accordingly the invention also consists inI burner plant comprising burner piping having jetk y in a series extending longitudinally. thereof, andsubstantially coextensive Vaporiser orifices pipngthrough which liquid fuel is passed to the burner pipingand upon which the flames from said jetsare directed to-act or. impinge.

The amount of heat required from fog dispell- REaaasa of 30 therms/yd/hr. capable of reduction to 20 or therms/yd./hr., or to be run at maximum of, say, from 35-40 therms/yd./hr, or more for wider runways. At the double burner lines at the landing approaches fuel consumption should be capable of being raised as high as 80 therms/yd./hr.

The burner pipes may be laid above ground,

the overall height being kept to a minimum, or

may be again started up at any time during the.

following hour or thereabouts without priming as the residual heat is suiicient to produce vaporisation upon the resupplying o f liquid fuel.

Troughed burners also enable a construction to be adopted whereby colourless or partially colourless llames can be utilised, if desired, by the induction and premixing of combustion air at the vapour jets. l

` vAnother form of plant according to the invention comprises long burner pipes above or below ground level fed with vaporised or gaseous fuel from a separate vaporising source. The vaporising equipment may be either remote from the burner line or may form part of the fog dispersing system. In the latter case, the heat evolved in the vaporising plants in excess of that required for vaporising the fuel fed to the burner line is available for fog dispersal. Y

. The vaporiser plant may be of blowlamp principle already indicated or may comprise a tubular boilerthrough which the fuel to be 'vaporised is passed and a furnace fed either from a separate fuel supply or with part of the fuel vaporised in the boiler.

.The burner pipes of each plant are drilled at suitable intervals along their length and hole sizes are so arranged to provide sympathetic lighting of the llames. Special stabilising jets may be provided, which remain alight under adverse atmospheric conditions, and facilitate relighting of the other jets if these are extinguished. Where the burner lines are above ground certain interruptions are provided for the ingress and egress of aircraft but it will be appreciated that every interruption constitutes a potential ingress area for fog and consequently their width should not be greater than that required for the passage of aircraft and the number of interruptions should be limited.

.Long lengths of burner and vaporiser pipes which are subject to expansion and contraction due to the temperature changes, are liable to cause difficulties, and in order to solve this prob,- lem vaporiser and burner piping is anchored or secured at a single point in its length-midway, or at one end only, thereby causing movement to take place freely either in opposite directions or` in one direction away from the anchorage.

Alternatively, more than one anchorage may be employed, and expansion and contraction accommodation bends in the piping or equivalent devices may be introduced as required in a unit or section.

The invention includes the provision of means for selectively controlling various burner lengths or lines in-order `to adjust both the disposition of `the heat and the heat units to be liberated, with respect to the landing strip, most effectively -and economically, according to the prevailing meteorological conditions aifecting the dispersal ofv fog-which include wind speed and direction, temperature structure of the lower atmosphere,

and the water Vcontent droplet size distributionr of the fog.

Hand controlled valves and automatic valves l of known type for regulating the liquid fuel supply including limitation of the pressure so that such does not exceed a predetermined maximum and further cutting olf the supply should the .pressure fall below a predetermined minimum are provided, and in large installations, particularly in those of a permanent character, it is desirable to employ means for exercising remote control and indicating means adapted to take care of the priming, lighting of the burners and indicating whether any particular line or burner section is alight ornot. Y f

In the accompanying `drawings which exem-` plifythe invention: y

Figure 1 is a diagrammatic plan, in two fragments,v illustrating a runway according to the invention with the landing strip and lines of burners and supply piping represented.

vFigure 2 is afragmentary enlarged diagrammatic plan of a boxv burner frame alighting end of the runway as seen in Figure 1.v

Figures 3 and 4 are respectively a plan and elevation of a burner unit (described hereinafter as the triangular burner), a series of which are employed according to one form of burner plant suitable for location above ground level on a runway, while Figure 5 is an end elevation and, Figure 6 a cross section thereof.

Figure 7 is a diagram indicating the vaporised jet location with respect to the vaporiser piping arrangement seen in Figures 3 to 6.

Figure 8 is afragmentary side elevation and Figure 9 a corresponding fragmentary plan of another form offburner unit or section (described as the trough burners) suitable for location4 below ground level .of the runway.

Figures 10, 11 and .12 are sections taken respectively on the lines I0, Il, I2 of these figures. Figure 13 is a fragmentary isometric view of another form of trough burner burner unit ac.

cordingto a modication of the invention.

Figure 14 is a fragmentary isometric view show-.rv

ment of a form of independent vaporiser andv burner conduit plant, according to the invention, for a runway.

Figure 19 is across section of the element seen in Figure 18 taken on the line |9-I9.

Figure 20 is a side elevation of the element according to Figure 19.

i Figure 21 is a detail rof, the vaporiser heater elenient of lFigure 19.r

elevation, a plan and a cross section of a tragmcnt of burner Aict conduit, Such es. Secc on .the right of Figure 18.

Figure25 is a fragmentary sideelevaticn and Figure 26 a plan o ftransportable burner plant embodying an independent vaporiser andburner pipeline according toca modidcation. of tho invention, and

Figure 2'1 is across section. taken on the lino 2 7 of Figure 276.

' In carrying the invention into eiect according to one mode, as described by way. of example, the runway comprises a landing strip I (see'Figure l) of the length and width required for the type of aircraft it is intended t leve, with the strip andy spaced from the lateral-margins 2 thereof a burner line heat source 3 is ,laid at a distance not substantially less than V50 yds. from each of said margins, and this pair of burner side lines is substantially continuons and coextensive with thelanding strip except for any gaps that it may benecessary to provide for the ingress and egress of groundedaircratt to and from said strip. Each extremity of theland- .Barallel ing strip has double burner lines 4 4 arranged transversely thereacross. It will be appreciated that the landing enmarca is chos enclosed by the side and transverse burner lines, which in effect form a burner heat source. frame.

Supplementary burner lindo-5 are laidy which are ddditional to and adjacent the Sido burner lines 3, alone thc .approach ends .extending a suitable distance inwards from the terminal lines. From the inward endsof the doubledypart of the side burner lines and `joining `them together a second transverse double burner line 6 is laid to `complete arectangular heat boi; of greater intensity at the approach end portions of the landing strip in order to ensure good visibility yfrom whichever direction longitudinally aircraft `approach the strip.

It will be appreciated thatthe Positionof the second orinward double transverse line of burners t is dependent upon the point at which the aircraft touch down as this transverse lineshould be crossed before the aircraft alight. `A suitable distance for the Second line has been foiled to be about 160 yds. frorn the first or terminal transverse double burnerrline 4.

In order to ensure that the heatedzone shall cover the landingstrip evenin cross winds of say, miles per hour, andfprevent the wind blowing the heated air s othat the ceiling of the fog free area is displaced beyond the landing strip, an auxiliary outer burner line may be installed, spaced from the centre` of the landing strip about D yds. This line may be broughtintothe heat frame by extending the transverse burner lines outwardly.

The burner plant according to one example, see Figures `4--7 (hereinafter referred to as th'e -triangular burner) in which the fog dispelling names also serve for vaporising the liquid fuel on its Way to the jets fromwhich said flames issue, comprises vaporizer piping in communication with burner piping. 'The piping islaid in sections or units of suitable length for feed and operational purposes and are placed end to end to constitute the burner lines framing the landing strip l as referred to above.

' Each unit consists of a pair of burner pipes 1 each composed of united lengths of steel tubing of 11/2 inches, the axes of `the pair of pipes being spaced apart horizontally about, '1; inches..

vaporiser piping 8 composed of united .lengths of steel tubing of 2 inches diameter is positioned above and runs coextensive with the burner pip- Ving 'l with its axis in the mid-vertical plane between the axes of the pair of burner pipes, so that the axes ofthe vaporiser and burner pipes 8 and .'I lie at the corners of anequilateral triangle, as viewed in cross section.

The burner pipes I are bored with jet orices about le-0f an inch. These jets are positioned at 4-to-6-inch intervals throughout the length of each burner pipe. The jet bores 9 are positioned so that the jets are directed upwardly and inwardly towards the vaporiser pipe 8 and the axis of each bore d is directed clear of the outer side of the vaporiser pipe 8 by about 1/2 inch Witha View to causing one or other set of the jet flames to impinge satisfactorily on the vaporiser piping and effect vaporisation of the liquid fuel sup,- plied thereto (under a pressure of about 25 lbs), whatever the wind condition and directionmay be, while in calm conditions or light winds the jets of both pipes impinge upon the vaporiser pipe.

The vaporiser and burner pipes 8 and 'I are positioned in their triangular relationship vby a series ofV transverse apertured plates or frames t0 (called spreaders) conveniently spaced at 6 foot intervals longitudinally. The pipes I and 8 pass through the apertures I I and I2 of the spreaders and are adapted to slide under expansion and contraction conditions.

The longitudinal vaporiser-burner lines parallel with the landing strip and elsewhere are madeup, as noted above, in units or sections suitable for feeding, combustion and operational conditions. According to one arrangement la vaporiser-burner unit is about feet in length and is formed in two sections A and B arranged end to end, the inner ends of the vaporiser pipes 8 being served by branch pipes I3 from a cornmon feed pipe ld, while each of the burner pipes "I at their outer ends are in fluid communication with the adjacent ends of the vaporiser pipes by means ofl a transverse pipe I5, the other inner ends of each burner pipe being closed. According to this arrangement it will be seen that vat their outer ends the vaporiser pipes 8 are united to the admission end of the burner pipes I so that relative longitudinal displacement between the burner and vaporiser pipes can take place and anydistortion dueto expansion or contraction is avoided, while vaporiser fuel has free access to the burner pipes from the vaporiser pipe. The transverse header or union pipe I5 is anchored to a concrete foundation block I6 by angles I1, the inner ends of the pipes 'I and 8 being free for expansion or contraction.

A pair of spreaders lil for each section (of which only one is shown) is located adjacent the inner ends and mounted in concrete blocks I8 and a spreader Il) is fixed to the block I6 adjacent each anchored end. Elsewhere the spreaders may be secured to the ground merely by spikes.

According to another form of burner plant in which the burner fog dspersing jets are again also used as vaporiser jets with the vaporiser` pipes coeXtensive with the burner pipes, see Figcures 8-12, both pipes are located in a trough below ground level so that the burner line installation offers no obstruction to the free passage of grounded aircraft across the burner lines. These vaporiser-:burners are hereinafter referred toas "trough burners.

Precast sectional concrete channels lIt! are sunniti: the ground aibng the-burnerlines-Aparallel with the margins of the landing 'strip and are similarly sunk for the transverse 'burner'flin'ea The concrete channels are adapted to receive lcast iron trough sections about 3 ft. 6 in. long and about 8-9 in. in width and depth, fitted to gether end to end to constitute a continuous trough. The under sidesof theiron troughv'secftions 20 are provided with transverse lugs 2| kdisposed centrally of their length and are adapted to engage in corresponding 'slots 22 in the concrete channels I9 in order to prevent cumulative unidirectional creep of the irontroughs due to the alternate expansion and contraction under heating and cooling conditions. The joints 23 at the ends of the troughs 20 overlap and have 4clearances to accommodate expansion of the troughs from their centre outwardly. These cast iron troughs 2t operate as heat storage capacities and retain heat over a period as above vindicated, which may be utilised in restarting without priming.

The continuous iron trough formed bythe sec'l tions 20 is fitted with vaporiser-burner units arranged end to end with a suitably short interval or space 24 between each end of a unit and the next. Each unit comprises an oppositely disposed pair of 1 inch diameter steel pipes 25, each in the form of a U tube or hair-pin of about 10 ft. in length. The limbs 25a, 25h of the hair-pin -form are arranged in the central vertical plane cf the trough 20 and are supported and located within the trough in frames or boxes 26 aperltured to accommodate the piping. The upper limb 25o of each hair-pin form functions as a vaporiser for the burner pipe limb 25a below it. The burner limb 25a is provided with jet bores 21 of about e inch diameter at 6-inch intervals which are adapted to direct the fog dispelling and vaporising jet flames upwardly in the midvertical plane so as to impinge upon the vaporiser pipe limb 25h. Y

The axis of the vaporiser pipe limb 25h is located about 11/2 inches below the horizontal plane of the lips 28 of the iron trough 20 andthe verti cal distance separating the axis of the burner pipe limb 25a, .from the axis of the vaporiser pipe limb 25h is about 3% inches. Under operating conditions liquid fuel is supplied at a pressure of V 20-40 lbs. per sq. inch. n

For priming purposes the burner units are provided with a fuel catchment tray 29 below the burner pipe limb.

The adjacent ends 25e of the burner pipe limbs 25a of a unit are closed whilst the adjacent ends 25d of the vaporiser pipe limbs are each connected to a short U-shaped feed section of pipe 3U extending through an aperture 3| in the trough and which is coupled by a T union 32 upona com;- n

mon fuel feed pipe 33 for the two vaporiser,- burner elements comprising a burner unit.

The adjacent inward ends of the hair-pin elements 25 are located in a support casing or box 25, the arrangement being such that expansion from which the sections are fed from theI liquid t ffuel supply main.

mtWithfa Avie'wf""to-=facilitating "the transiti-'of grounded aircraft across the burner troughea grid v34-is provided over the trough mouth. The y lips of the trough are provided with a serieslfof slots 35 spaced apart about 6 inches and in register with" the burner jets, and are adapted to receivetransverse grid bars 34a which are secured 'a's by welding to longitudinal grid bars 34ml). I'

The width of the troughs 2U and vthe central l*position of the vaporiser-burner pipingY 25 are such as to leave ample clearance for the ingress of combustion air for the burner jets 'over the lips of -the trough, and in normal wind or calm condi'- tions'the jet flame isA of a stable, highly luminous character.

A partially colourless or a colourless or Bunsen flame may be produced in trough burners by arranging for the burner jet to operate with an in- `rjection action calculated to induce auxiliary'air vto flow to the jets below the base of the flames so that there is a premixing of vapour and air. This laction may be produced by suitably locating the vlongitudinally extending grid bars 34D (vertically positioned and laterally spaced from the jet orifice vertical plane) between which the base or lower portion of the flame is located whereby the high velocity flame is caused to issue through an induction slot and draw in air through the slots formed at each side between the Ybars 34D and the lips 28 of the trough. i vThe longitudinal grid members 34h may be about 1/2 inchl in thickness and 11A; inches in depth and spaced apart Vabout 41/2 'inches and located equally from both :sides of the central plane vof the troughs.' vaporiser-burners provided with this induction air arrangement are referred to hereinafter as .trough slot burners.

Seatedat the edge of the concrete channel and adjacent and flush with the lips of the trough, a continuous run of concrete slabs 36 maybe laid in order to provide a firm edging for trallc. Y An economiser .pipe comprising a U tubear- `ranged at the lower part of the trough 20 so that legs thereof are adjacent the sides .of the -trough may be provided into which the liquid fuel is passed from the feed pipe 30 before it passes into the vaporiser limb 25a. Such economiser pipe may extend` substantially the whole length of the vaporiser burner unit 25.

`According to another form of plant adapted to be located in ametal trough (see Figures 1:3-17) the unit or assembly comprises a pair of spaced vaporiser coils 15 each formed of SAQ' borel tube and consisting of 271/2 turns at 1% pitch. These coils vaporise the oil and feed it to a top burner pipe 16. The oil is fed into the .coils from pipes 'l1 lying at the bottom of the metal trough 18 which is located in a concrete trough 18. The pipes 11 are'fed by transverse feed pipes connected to a common feed (not 'shownX y j A vaporiser burner is locatedbetween the coils J5 and comprisesaring 8| mounted in avertical YVplane' and provided with horizontal jetsv 82g'9n both' sides, there being four jets on each side.

' The feed to the burner ring 8| is obtained by connecting the vringto the top .burner pipe '15, the feedbeing in vapour form. Y' j r A secondary feed to the burner pipe 16 is provided'by means of the pipe v82 which comi municates Ywith thevburner ring `8| vand from f'which a'riser' pipe'84 is connected tothe pipe 18 adjacent I the liquidr phase end .of vthe coilv 15. "j "Theburner tubgfl. '1ST Simeone@ inlth' trough upon spaced tripodsn 'andusrdrilled fatt engages? intervals `with Morse vNo., 46 holes 86. vEach burner'tube 16 is provided with a stabiliser jet `8'! approximately 2 ft. -6 inches from one end. Such jet consists of 1/8" gas piping long welded over one of the jet holes =86. The stabiliser jets are provided so that if owing to ad'- verse wind conditions, the flame is blown off a number of the jets 86, fthe stabiliser jet continues to burn and thus reignites the blown out jets.

Each burner tube 1B is vprovided with an oriiice plate 88 (see Figure 17) having an orice of about 1/8 located-at a position marked X, i. e. between the point where the vaporising coil 'I5 communicates with the burner tube and the point where the pipe'lS communicates with the vaporiser burner 8|.

These orifice plates control the amount of vvapour being fed into the burner tubes in proportions suitable 'for effecting even flame lengths at all parts of the burner tube.

Orifice plates are also fitted at the feed end 'of the pipes 80 the function o'f these being to eliminate the possibility Aof burner surge due to the employment yof once throughv type vaporiser coils. vThe employment of orifice plates in the feed pipe 99 also has the advantage of ensuring less possibility of the burner being overloaded and producing smoke.

The ow of oil and vapours is shown by the arrows in the diagram Figure 15.

In carrying out the invention `according to another example employingl a burner plant in which the fog dispersing jet flames of the burner lines Iare notemployed'also to providethe va-` porising source of heat (although vaporisation is produced by alongitudinal set of burner jets impinging upon vaporiser Itubing), a vaporiser section or unit line is installed from which burner piping (called the burner jet conduit) for proconduit plant, the vaporiser part with its set of burner jets being styled the vaporiser element.

The vaporiser element comprises a bank `or stack of vaporiser tubes `l3'! (Figures l8-'24) and a-burner jet heat sourcearranged in a concrete trough 38 about 3 ft. wide Vand 2 ft. 2 inches deep, sunk 'in the ground. The concrete channel may conveniently be composed of precast sections. vThe metal piping vand'associated metal parts operate as heat storage 'capacities in a similar manner to'that above'in'dicated in connection with the trough `or trough slot burner plant and enable the vaporiser elements, 'after use. to be restarted without priming.

The bank ofvaporiser-tubes 31-may lcomprise any-suitable number space'dvertically and horizontally as'viewed in cross sectioninsucha manner'that they "are accessible tothe flames from the elongated 'flame source `tillocatedbelow the In "the present example, sixteen `2inch internal diameter `steel tubes 130 "ft. long are spaced at about '4l/pinch pitch ina square'arrangement and supported in apertured rspreader plates 49 which lare positioned' in notches or grooves 4l "formed l"in the Asides Ao'f the trough.

The spreader plates40 comprise 4fa "base section 49a having side grooved 'guide arms 4Gb Vwhich seat in the grooves lll and a series of bars i400 the ends of which Vare located inthe 'grooves o'f the guide arms vfdllb. 'The'basesection 40a and the .l0 bars 'lille are provided with semicircular recesses 49d which co-operate lto 'formthe vapertures'for the vaporiser 'tubes 31. The bars 49e are retained in place byfcaps'lle bolted to the'guide arms 49h.

The central longitudinal vertical plane of the bank of vaporiser tubes 31 is disposed in the corresponding plane of the trough 39 and oneach side ofthe bank depending vertical plates or partitions 42 located in slots in the bars 40o are positioned between the spreader plates'40 to confine the ames on fthe one hand, and `on vthe other to provide a pair of lateral channelways i3 for the ingress of air to the jet flames beneath lthe bank.

Below thebank andspacedtherefrom with its axis in the centrallongitudinal vertical plane of the bank, a burner or heater vtube 39 is positioned by a pair of jaws 45,1'1I6, carried by thebase'sec-` tion 40a of each spreader, one jaw 4B of which may be made removable forlconvenience in installation. The jaws l5, B6 and the `sides ofthe tube may be provided with complementary engaging slot 'and projection means '41 to prevent the tube turning in the jaws while permitting longitudinal Iexpansion and contraction movement.

The burner tube `39`has three parallel sets of longitudinally spaced jet orifices 48a, 48h, 48e (Figure '21) of about le inch in diameter, 'the jets of the sets 'being arranged staggered so that the jets of all the setsr'are spaced about '4 vinches apart longitudinally while the jets 'of Ieach set are about 1 ft. apart.

One of thesetso'f jets 48bis in along'itudinal central plane of the'bank and axis of the jet tube 39 so that the jet-s issuing from this settare directed vertically. 'The Vsets 48a, -Vl8c Aon each side of the central set are spaced 'from the latter about 4%4 of an inch measured circumferentially, and are bored 'to diverge outwardly, the vangle being chosen such that the centres of the flames from these jets will normally pass inward of the outer tubes 31 o'f the lowest four ofthe bank.

y Each vaporiser tube 3'1 is -connected toa `1inch diameter feed pipe '49 at one end so that fuel is supplied from a feedbranch in parallel to all 'the tubes. The other ends-of the tubes, with the exception of the pair'31a of the'lowermost group of tubesy which lies next thefcentral verticalplane of the bank (see Figure 19), enter a common charnbei` 50 which acts asa mixing compartment and feeds the burner .iet conduit 5l with fuel vapour. The two tubes 31a l(excepted above) are bent downwardly at their `ends -an'd are connected to a cross tube 52 supplying fuel from'the Atwo'tubes to the longitudinally extending heating or burner jet tube 39 referred to above, theother Aend of which is closed.

The burner jet conduit 5| i-s laid'from the com mon chamber 59 either in direct longitudinal extension of the vaporiser element, along the burner lines vplanned for thellanding strip, in which case the vaporiser jet flames also serve as Ipart of the 'fog dispelling "burner'line, or if desired is bent and extends 'at a fright-angle or vother suitable angle with reference to the vaporiser element.

This conduit 5l is of 8inch diameter mild steel (steam quality) piping laid in sections. Where very long lengths lof conduit are employed the part Iaway from'the vaporiser element may be offsmall'er 'size (for example 6-inch diameter) to `allow `for 4the ydecreasing amount passing ldown the pipe. Along Ithe -conduit v5| are 'formed a vcontinuous series 'of -og -dispelling jet orifices about T16 of an inch diameter, which may be flared and spaced apart longitudinally about 3! double orifices are provided the axes of which converge towards one another so that the flames issuing therefrom impinge thereon bats-wing fashion, the purpose of which is to facilitate the running ignition of the name at starting or to relight any adjacent ames that may be temporarily extinguished.

The conduit 5| may be laid upon the ground surface but it is preferred to dispose of it in a concrete trough |52 sunk to substantially ground level so that the horizontal tangent at the top of the conduit 5| lies in the plane of the lips of the trough.

. The trough |52 is about 13 in. width inside measurement and about in. deep.

The conduit 5| is supported at intervals of about ft. upon cross tubular members 53 of carriers 54 of H form which are sunk in the concrete and which are accommodated in grooves 55 in the side of a concrete channel formed partly in one section and partly in the other at the section joints. Retaining members 5B telescoping into the H members are provided having lips 51 which extend over the conduit 5| to counteract upward movement of theconduit 5| due to dis-4 tortion caused by the heat.

The feed pipes 49 for the vaporiser tubes 3T are located in a concrete trough |56 closed by slabs |51 and bars 58 and are coupled to a main feed 'pipe' 59.

The two vaporiser tubes 37a connected to the` burner jet tube 39 are fed separately by pipe 49o. connected to a main feed pine B0.

The burner jet conduit 5| served bv a vaporiser element may be from 300 yds. or more in extent,

according to requirements and limitations im# posed by condensation and this conduit carries the Vapour supply for the burner jets. .The end of the conduit 5| remote from the vaporiser is provided with a steel vessel for collecting condensate which forms during the starting up of the burner. The condensate collected in this vessel is disposed of. when necessary. either by means of pumping out the vessel or, alternatively,

the vessel may be connected to a vaporising pipe or coil situatedy parallel with the burner pipe so that the heat therefrom will vaporise the condensate in the supplementary lpipe or coil. which is burnt in an attached oriiced auxiliary burner tube. In installing independent vaporiser and burner conduit plant at the intersections.V of runways or elsewhere in positions in which it is essential that the burner flames can be extinguished immediately should vit be necessary to pass aircraft over such locality, a by-pass and blow downf line is suitably connected with thesupply from the vaporiser feed chamber or with the burner jet conduit adjacent thereto, the connection being provided with a pair of inter-connected vtwo-way valves. When these valvesy are in one position the vaporiser feedsstraight through to the burner jetconduit, while when it is required'to shut oi the burner jet conduit completely, to extinguish the'ilames, the valves are operated to by-pass the vapour away from the burner jet conduit into the by-pass line and so that the burner jet conduit is vented down the blow down line.

The by-pass line is'v provided -with jetorifices and is virtually a secondary burner. The vapour from: vthe-vaporiser` element passesout through thesei crices and idly burns, thus yenabling the vapor-- iser to be shut down at leisure; or Vthe burner jet'- conduit may be switched in again when only a temporary extinction of its flame is required.

At intersections of `runways and the like the vaporiser `element-may conveniently be installed to lie at right-angles to the burner jet conduit, and instead of running in one direction the latter may extend in opposite directions away from the vaporiser element which-serves both branches.

In order to provide readily transportable plant for rapid erection or temporary use, independent vaporiser and burner conduit plant may be provided comprising a relatively small vaporiser coil unit adapted for coupling with lengths of burner jet conduit of suitable diameter. In this example of the invention (seeFigures 25-2'7) a vaporiser unit consists of six vaporiser helical coils 62 mounted upon Va 'v rectangular tubular frame 6311 which also operates as a liquidvfuel supply dis tributor for the coils, and is adapted to be laid on the ground'withilittle or no preparation. Along each of the longer sides of: the rectangular frame 63 the helical vaporiser coils (of about 9 inches in diameter) are mounted; for example, three coils B2 may be positioned at each side of the rectangle, coupled together in pairs by pipes 64 across'the rectangle so that each c-oil of a pair functions in series, while the pairs are coupled to a frame tubing through the side 65. The burner jet tube 66 for providing the vaporisingfiame for. the coils is located-centrally of the rectangle 63 and is connected at one end to the pairs of coils by pipes 69. The burner tube 66 has two series of jet orifices 61 located uponeither side of the longitudinal vertical plane-containing. the axis'of the tube,

the orifices being bored with their axes at about 2530-to the horizontal so as to direct vthe flame from one set of orifices towards one set of vaporiser coils and the -other set of orices is directed towards the other ,coils asindicated bythe dotand-dash lines in Figure .27.. f

Thetubular frame 63and burnery tube are connected toa feed line 68'for Athe fuelsupplied from a main, and according to the preferred arrangement'a burner assembly comprises two such framed coil units as described above, placedlin longitudinal extension one of the other with a space between, which may be occupied by a. U-shaped pipe feeding both elements from A.a feed pipe entering'the vU-shapedl pipe T fashion. At the oppositeends the-vaporiser elements are connected to burner jet conduits |69 which `may be laid in-straightvlines Yrunning away from'the vaporiser elementsandare connected to the vaporiser burner tube GBby a cranked union 1U, thewhole being weldedvtoxtheframe 63 by a strap 1|.. `"I'he conduit.. .|69v comprises 2-.inclfrin-- side dimension steel,f.(steam equality)4 `tubing, arranged in 20 ft.' lengthspcoupled together by unionsf- At the-.end or-Lat intervals thefconduit is provided withanaperturedbracket 12 having feet or flangeswhich supportthe tubing upon the ground. The conduit tsfslidably` in the apertures inthe brackets sothatexpansion may take place outwardlyvAt intervals of about` 6 ft. .3 triple orifices` may fbe -provided'lfor forming flames of bats-Wing type Ato facilitate the running ignition .ofA the fiame as in a previous modiiication. l The sections or'lengths ofburner-jet conduit are provided .Witha; series ofyvertical jet orices l3` 'I3 of about es inch diameter and the spacing interval is about 3 inches. The total length of a vaporiser element and its burner jet conduit is about 84 ft., of which 76 ft. is burner jet conduit while the remaining 8 ft. is occupied bythe vaporiser element. Allowing for the space between vaporiser elements the overall dimensions of a pair of units is about 174 ft.

The whole installation is designed so that it can be moved, with all the necessary spares and erection tackle, on ordinary lorries, and weights can be kept within the capacity of three-ton' lorries.

Each burner plant requires a storage reservoir for liquid fuel, conduits to pass liquid fuel to the pumping station and pumps necessary for establishing and maintaining the required pressures. Any appropriate form of various alternative layouts available of the main and distribution branches may be adopted, such as of the character indicated herein for supplying the burner jet pipingT or burner tubes of vaporiser elements with liquid fuel.

Thus, referring to Figure 2, which shows diagrammatically suitable controls for supplying fuel to the burners at the right-hand end of Figure l, from the pump house 90 a pair of main pipe lines 9|, 92 extend. The main 92 supplies four sub-main pipe lines 93, 94, 95, 96 which supply fuel to the units along' the adjacent burner line 3 and certain of the units in burner line 5.- These sub-main pipe lines 93 to 9B are controlled by hand-operated stop Avalves 91.

The main 9| extends to the other side of the landing strip I and supplies similar sub-mains 98,' 99, IDU, IDI underl the control of handoperated stop valves IDZ.

The main pipe line 92 also supplies a sub-main ID3 under control of a hand-operated stop valve |94. From the sub-main |93 branch pipe lines |05, It, Il'I, |08 supply under individual valve controls the units in the supplementary burner lines 5 on the near side, the units in the transverse double burner line 6, the double row of burner lines on the near 'side and outwardly of the burner line 6, and the units on the double transverse burner line 4.

The main pipe line 9| supplies a similar submain H39 under control of a hand-operated stop valve I I9 from which branch lines I I I, I I2 which supply under individual valve controls, the units on the supplementary burner lines 5 on the fa'r side, and the double row of burner lines on the far side and outwardly of the burner line 6.

The pipe lines IIS connected directly to individual sections of the burner lines are each provided with a valve H4 to give individual control for each section.

The controls on the liquid fuel supply for each unit or section of a fog dispelling burner line are provided with appropriate hand control cocks and with pressure responsive valves for regulateing the supply of liquid fuel to a predetermined pressure (of, for example, 18 lbs. per sq. inchl" is supplied and ows to burner jets in a predetermined quantity measured by duration of flow or by the release of a metered quantity, for the purpose of providing a priming supply for initially heating up `the lvaporiser piping or tubes. When 14y priming has been effected, which may be electrically indicated at 'a station remote from the burner lines, the jets of the burner lines or sections thereof maybe lit in a continuous run or in a predetermined sequence, by electrical or other igniting devices operated either manually or automatically after 'a time interval following the commencement of priming.

Temperature responsive devices may be installed'at suitable points in a burner line or at each section to indicate at a control station whether the burner line or section'in the vicinity of the devices isalight or is extinguished.

Sections of burner piping or a burner jet conduit may be provided with vapour pressure responsive devices and remote indicating means to indicate the state of vapour pressure stage reached in starting up or the condition during operation.

In each of the plants described the flow of liquid fuel to the vaporising tubes or pipes may oe controlled to prevent surging by the insertion of an oriced diaphragm vat the feed junction, and similar oriiice'd diaphragms may be located in burner jet pipes or conduits to control the rate of flow of fuel vapour.

If the wind and atmospheric conditions and factors governing any particular fog are known, then the heat output requirements necessary to disperse the fog could be forecast. In practice, however, it is scarcely possible to measure all the factors sufficiently quickly to apply the information, and in any case it will be evident that a great many varieties exist. Consequently the expedient of trial and observation of the dispersal produced should be adopted and tables for future guidance prepared.

In operation, having selected what burner lines or parts of lines will be required to deal with a fog under the prevailing wind and other conditions, the selected burners are primed. case of the triangular burner plant and the trough or trough slot burner plant, a priming quantity ofy liquid fuel .is released and flows from the jets onto the ground or into the catchment trays and is subsequently ignited. When this fuel has all but been consumed, or after a predetermined time (found by experience) and vaporisation in the vaporiser piping is taking place sufficiently for the pumps to set to work to raise the pressure of the liquid fuel supply gradually in stages,

and as the vaporised fuel burns at the jets and supplies more heat to the vaporiser piping, continuous vaporisation will become more perfect until the appropriate normal working pressure can be employed, An installation for a full-sized landing strip of 3,000 yds. with subsidiary runways may require 10-15 mins. in starting up.

Pressure is maintained at 13 lbs. per sq. inch or such other pressure is appropriate for the particular plantin operation to secure the output predetermined or approximately estimated nec-v essary to dispel the fog.

Duringl operation adjustments may be made according tothe'observed results, both in the burner lines or sections ignited or in the pressure to alter the' therm/yd./hr. output.

After the aircraft, for the guidance of which the installation has been put into operation, have been landed. the fuel pressure is gradually reduced and the operating valves are shut down manually or automatically when the pressure has fallen below the predetermined minimum.

In the operation of the independent vaporiserand burnerA conduit plant a similar procedure is' In the assunse pursued but in :this case priming takes; placefatthe; vaporiser element and the ignition of the ljet of; the burner conduit takes place more gradually along theV conduitas the required vapour conditionbecomesestablished along the conduit. ..-;When all the jets of theconduitv are ignited the fuel pressure is raisedin suitable stages and shutting down is effected by shutting of the controlling valves; f r-'Substantially thesame loperation is carried out for the smaller or transportable independent Vaporiser and burner conduit plant but as it is usu. ally not necessary to provide this plant with automatic devices,v the vaporiser elementl is ignited by hand and the control valves are operated manually. v f

; We claim:

1.y A fog'freeable aircraft runway comprising a. landing strip and burner lines extending longitudinally parallelA with but spaced from said strip ajnd transversely across the approaches to afford a linear heat sourceor frame by the consump' tionof fuel in the burnerlines at a rate to develop that number of therms/yd./hr. capable of producing a fog-free tunnelor rift over the landing strip.

2. A runway as claimed in claim 1 wherein adjacent the approaches to the landing strip each of the burner lines extending longitudinally and transversely comprise a plurality of parallel burner pipe lines to secure increased fog dispersal.

3. A runway as claimed in claim 1 wherein the burner lines extending transversely each comprise burner pipe lines across the ends of the landing strip 'and burner pipe lines extending transversely across the strip and spaced from the pipe lines across the ends of the strip, the arrangement being such that the said transverse burner pipe lines together with the adjacent portions of the said longitudinal burner lines constitutes a box form in plan.

4. Plant for a fog freeable runway as claimed in claim 1 wherein the burner lines which extend longitudinally of the runway each comprise a series of aligned burner units, each consisting of rectilinear lengths of burner piping having a series of fog dispelling :llame jet orifices, vaporiser piping above and coextensive with said burner piping, the vaporiser piping being disposed and the said jet orifices being directed to cause the fog dispelling flames to impinge upon the vaporiser piping to vaporise fuel passing to the burner piping, fuel supply branch piping coupled to the vaporiser piping of each unit, and continu-` ous fuel supply piping coextensive with the said burner lines and coupled at intervals to the said branch piping for supply of fuel thereto.

5. Plant as claimed in claim 4 wherein the said vaporiser piping comprises pipes extending in opposite directions from the said supply branch piping.

6. Plant as claimed in claim 5 wherein each burner unit is composed of two sections extending in opposite directions, each section comprising a pair of parallel jet orificed burner pipes closed at the adjacent ends of the sections, a vaporiser pipe extending longitudinally in the mid-vertical plane between said burner pipes and at a level above them to constitute a triangular arrangement of burner and vaporiser piping as viewed in cross section, a. header at the outer end of each section to which both the burner and vaporiser pipes are coupled and branch supply pipnsfcdupledfto thefvaporiseripiping at thefadf' jacentl ends of eachfsection. y. 1

7;,` Plant as` claimedin claim 6 and compris-` ng a series offspreaders havingga rtriangular ar-K, rangement of pipe receiving-.apertures :for glocat; ing-and supporting-@the burner and vaporiser pipes at,intervals.longitudinally and anchorage means for fixing the outward ends of the burner sections in relationgto theiground.- ,f

8. Plant for a fog freeable runway as. claimed in claim 1 and comprisingheat conserving metal troughing for location: below ground level on the lines for the burners, burner line components the form ofiiame jet oriced piping and vaporiser piping `in the troughing, supporting means l within the troughing for disposing the vaporiser piping above the burner piping and sucnthat the yjet flamesimpinge on the vaporiser pipingas, well as serving forV fog dispelling purposes, and wheeled trafcv` supporting grids' covering said troug-hing and burnergpiping. r

Q "Pla-nt as claimed` in claim 8 wherein the burner and vaporiser piping comprise burner piping closed at one end and vaporiser piping connected to the burner piping at the other end of the burner'piping to form a U-shaped element, the limbs of which lie in the mid-vertical plane of the troughing with the vaporiser piping above the burner piping so as to be impinged by the burner jet llames, and a fuel supply branch coupled to the free end of the vaporiser piping.

10. Plant as claimed in claim 9 and comprising partition members positioned in parallel spaced relationship with the mid-Vertical plane of said troughing and the marginal edges of the troughing, to facilitate the induction of supplementary combustion air between said partitions and the trough margins.

11. Plant as claimed in claim 10 wherein the burner and vaporiser piping is disposed in units each having two of the said U-shaped elements extending in opposite directions from the branch supply piping which is disposed between the inward ends of the U forms.

12.' Plant as claimed in claim 11 wherein the partition members are formed as longitudinal bars of the wheeled trarlc supporting grid.

13. Plant for a fog freeable runway as claimed in claim 1, comprising a burner conduit having a longitudinal series of fog dispelling flame jet orifices and extending in a length along a suitable portion of a burner line, an independent tubular vaporiser for supplying vaporised fuel to the burner conduit and including jet oriced heater tubing and vaporiser tubing above the heater tubing coupled to said burner conduit.

14. Plant for a fog freeable runway as claimed in claim 1, comprising a burner conduit having a longitudinal series of fog dispelling name jet orifices and extending in a length along a suitable portionof a burner line, an independent vaporiser for supplying vaporised fuel toA the burner conduit and including a bank of spaced vaporiser tubes, a jet oriiiced heater tube below said vaporiser tubes and to which certain of said vaporiser tubes are connected, a mixing chamber at one end of the bank to which chamber those vaporiser tubes not connected to the heater tubes are coupled, a connection coupling the mixing chamber to the burner conduit and fuel supply connections for the vaporiser tubes at the end remote from said mixing chamber.

15. YPlant as claimed in claim 14 wherein the bank of vaporiser tubes and the heater tubes are located in a heat conserving trough, and where- 17 in Vertical partitions are positioned longitudinally between the sides of the bank and the trough walls to confine the flames of the heater tube jets and to afford lateral ingress for supplem mentary combustion air.

16. Plant for a fog freeable runway as claimed in claim 1 wherein the burner lines for the runway comprise lengths of fog dispelling flame jet oriced piping or conduit extending longitudinally along said lines and having stabilising jets spaced at intervals along said piping, each stabilising jet being formed by a pair of orifices inclined towards each other, for reigniting adjacent fog dispelling jet flames extinguished by wind, and vaporiser piping for supplying vaporised fuel to said jet oriced piping or conduit.

17. Plant for a fog freeable runway as claimed in claim 16 wherein the stabilising jets each comprise a pair of orifices inclined towards each other to produce a flame spreading longitudinally of the piping for reigniting adjacent fog dispelling jet iiames extinguished by wind.

18. An installation for a runway for rendering it free of fog for aircraft alighting purposes comprising: burner piping having a longitudinal series of fog dispelling ame jet orices, the said burner piping being arranged in lines parallel with and at the sides of the landing strip of said runway, burner piping having a series of fog dispeiling flame jet orifices arranged transversely at the ends of said landing strip, pipe lines for supplying fuel to the said longitudinal and transverse burner lines, the arrangement being such that the said burner piping provides heat sources by the consumption of fuel in the burner piping by aid of the jet orifices at a rate to develop that number of therms/yd./hr. capable of producing a fog-free tunnel or rift over the strip.

ARTHUR CLIFFORD HARTLEY.

JOHN CECIL BROWN.

GUY STEWART CALLENDAR.

HANS REINHARD FEHLING.

DENYS ANTHONY FOX.

FRANK GILL.

WILLIAM THOMAS MOORE.

PAUL OTTO ROSIN.

GERALD JOHNSTONE WILLIAMSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 401,258 Drake Apr. 9, 1889 966,395 Gothan Aug. 2, 1910 1,030,211 Stratton June 18, 1912 1,322,771 Eisenbach Nov. 25, 1919 

